US President Donald Trump announced on Twitter Thursday morning that his “highly anticipated” meeting with North Korean leader Kim Jong-un would take place in Singapore on June 12, saying that they will try to make the summit “a very special moment for World Peace”.

Trump tweeted his announcement about seven hours after he welcomed three Americans who had been held in North Korea when they returned to the US at Joint Base Andrews, a military base in Maryland, early Thursday morning.

The US president said he hoped to reach a deal with Kim on North Korea’s denuclearisation that could exceed people’s expectations.

“We will see if we can do something that people did not think was going to happen for many, many years,” Trump said during his remarks at the arrival of the released Americans, Kim Dong-chul, Kim Sang-duk and Kim Hak-song.

The highly anticipated meeting between Kim Jong Un and myself will take place in Singapore on June 12th. We will both try to make it a very special moment for World Peace!

Trump – who will be the first sitting president to meet a North Korean leader – said that he favoured holding the meeting at the demilitarised zone separating the Koreas, but that most of his advisers argued for holding it at Singapore.

A spokeswoman at Singapore's embassy in Washington told the South China Morning Post that Singapore was “pleased” to host the meeting, adding: “We hope this meeting will advance prospects for peace in the Korean Peninsula.”

The date and location of the summit are believed to have been finalised during US Secretary of State Mike Pompeo’s second trip to North Korea earlier this week to firm up Trump’s agenda for his meeting with Kim.

After his meeting with Kim, Pompeo told reporters when he arrived at Yokota Air Base in Japan on Wednesday that the two had “a good and lengthy conversation” in preparation for the summit.

And in the wake of the meeting, North Korea released three Korean-American detainees. As he met them on their arrival in America, Trump said he believed Kim wanted to bring his country “into the real world”.

“I think we have a very good chance of doing something very meaningful,” Trump said. “My proudest achievement will be - this is part of it - when we denuclearise that entire peninsula.”

The two sides have not yet made their conditions public about the denuclearisation negotiations. The Trump administration has stated that North Korea should make “a complete, verifiable, irreversible dismantling” of its nuclear weapons.

But the swiftness in the development of events concerning North Korea has analysts anticipating potentially historic outcomes.

“The pace of consultations suggests to me that we are closer to a major breakthrough on DPRK denuclearisation than ever before, ” said Dennis Wilder, a former chief of China studies at the Central Intelligence Agency and senior East Asia director at the National Security Council under President George W. Bush.

“It suggests that a major deal is under consideration that involves major concessions on each side,” he added.

Joseph Yun, former Special Representative for North Korea Policy at the State Department, noted the unprecedented nature of recent diplomatic efforts.

First came the summit meetings in late April between Kim and South Korean President Moon Jae-in at Panmunjom, in the demilitarised zone, and the joint declaration seeking to bring a formal end to the Korean war and establish “a robust peace regime on the Korean Peninsula”.

That cleared the way for the sessions now set between Trump and Kim.

“The key is to make the two summits consistent,” Yun told a Centre for Strategic and International Studies (CSIS) event on Monday.

“Kim Jong-un has three or four decades to look forward to [in his control of North Korea],” Yun said. “The only option for him to rule in comfort is to change the course [of nuclear and missile weapons programmes].”

Cho Yoon-je, the South Korean ambassador to the United States, said at the CSIS event that “we must take this rare opportunity to make diplomacy work before it slips through our fingers”.

The ambassador cautioned that the Trump-Kim summit must address the issues of “how to translate those gestures into concrete results” and “how to ensure North Korea won’t back out” from its promises.

Thomas Byrne, president of the New York-based Korea Society, also warned against too much celebration.

“So far, so good, but the actual work hasn’t begun”, Byrne said, referring to the eventual need for complete, verifiable, and irreversible denuclearisation, which will require “unfettered access for inspections”.

“The rubber starts to hit the road on June 12,” he added. “I don’t think in one meeting we’ll come out with a real framework or road map. I wouldn’t say an inability to reach agreement on the first meeting translates into failure.”

Still, he acknowledged, “even the sceptics, who look at the history of the negotiations with North Korea, look upon this as an opening for a breakthrough … I don’t get a sense that there’s a significant number of people saying it’s just a trap and to stay away.”

Japan also welcomed word of the US-North Korea summit meeting on Thursday, hoping it would also pave the way for resolution concerning the abduction of Japanese nationals by Pyongyang.

If the issues of the abductions and North Korea’s nuclear and missile programmes are resolved, “that would clear the way for economic cooperation for North Korea”, a government source was quoted as saying by Japan’s Kyodo news agency.

Noting that Trump showed his commitment to pursue the abduction issue during a meeting with Japanese Prime Minister Shinzo Abe in April, another government source told Kyodo, “We are pinning our hopes on it.”

Earlier on Thursday, Vice-President Mike Pence told NBC’s ﻿Today programme that “in this moment, the regime in North Korea has been dealing, as far as we can see, in good faith”.

Pence said that despite Trump’s recent praise for Kim, the administration was not ignoring the North’s abysmal human rights record.

“We have no illusions about that,” he said, but added that “North Korea has taken steps that indicate this may be an opportunity for a breakthrough” on the Korean peninsula.